Sperrylite
Sperrylite was first described by H. H. Wells in 1889 from material collected at the Vermilion mine in what is now the Sudbury district, Ontario, Canada. He named it for Francis L. Sperry, chief chemist with the Canadian Copper Company of Sudbury, who collected the original material in 1887 (Mitchell 1985). Sperrylite is a platinum arsenide mineral and is an important ore of Platinum. In fact, other than native Platinum, Sperrylite is the only Platinum ore of any significance. Sperrylite is found in abundance only at Sudbury, Ontario, Canada where it is mined for its valuable Platinum content.
Sperrylite belongs to the Pyrite Group of minerals. Sperrylite and Pyrite share a similar structure and therefore similar crystal habits. Other than crystal shapes, they do not look alike though because Pyrite is a brassy yellow and Sperrylite is tin-white in color. Sperrylite gems are extremely rare and valuable. Faceted gems are very attractive with their high metallic luster.
Locations: In Canada, at the Vermilion [TL – Type Locality], Victoria, and Frood mines, Algoma district, near Sudbury, Ontario. In the USA, at the New Rambler Cu–Ni mine, Medicine Bow Mountains, east of Encampment, Albany County, Wyoming; in the Key West mine, east of Moapa, Bunkerville district, Clark County, Nevada; and from the Stillwater complex, Montana. In the Bushveld complex, on the Merensky reef, Transvaal, South Africa, fine crystals from the Tweefontein Farm, near Potgietersrus; also at the Atok, Onverwacht, and Rustenburg mines. From Antamponbato, Madagascar. In China, from Danba, Sichuan Province; and Shiaonanshan, Inner Mongolia. In Australia, at several deposits east of Broken Hill, New South Wales, and at Kambalda, 56 km south of Kalgoorlie, Western Australia. In Russia, large crystals from the Talnakh area, Noril’sk region, and at Nikolaevsky, Amur, Siberia; in the Konder massif, Aldan Shield, Sakha; and elsewhere. In Finland, at Rometölväs Hill, in the Koillismaa complex; from the Hitura Cu–Ni deposit; and in the Siikakama intrusion.
| Chemical Formula: | PtAs2 |
| Platinum Arsenide | |
| Molecular Weight: | 344.92 gm |
| Composition: | Arsenic | 43.44 % | As | ||
| Platinum | 56.56 % | Pt | |||
| 100.00 % |
| Crystallography: | Isometric – Diploidal |
| Crystal Habit: | Commonly well crystallized as cubes and cubo-octahedrons, to 5 cm; may be highly modified with rounded edges and corners; as intergrowths with Pt–Fe alloys. |
| Twinning: | None |
| Cleavage: | Indistinct on {001} |
| Fracture: | Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 6.0 – 7.0; Vickers: VHN100=960 – 1277 kg/mm2 |
| Density: | 10.58 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Tin-white |
| Transparency: | Opaque |
| Luster: | Metallic |
| Refractive Index: | Isotropic. R: (400) 53.6, (420) 53.6, (440) 53.9, (460) 53.9, (480) 53.9, (500) 53.9, (520) 54.0, (540) 53.9, (560) 53.8, (580) 53.7, (600) 53.5, (620) 53.1, (640) 52.7, (660) 52.3, (680) 51.9, (700) 51.4 |
| Birefringence: | 0.000 (Isotropic) |
| Dispersion: | n/a |
| Pleochroism: | n/a |
